Note-frequency remote control installation



March 19, 1946.

H. FROHLICH NOTE-FREQUENCY REMOTE CONTROL INSTALLATION Filed June 19, 1942 l "I III III III lll lll HW W W MW 4 I. L- OJ mm (M v M I Patented Mar. 19, 1946 NOTE-FREQUEN CY REMOTE CONTROL INSTALLATION Hans Frohlich, Zug, Switzerland, assignor to Landis & Gyr, A. G., a corporation of Switzerland Application June 19, 1942, Serial No. 447,735 In Switzerland October 29, 1941 3 Claims.

The invention relates to note-frequency remote control installations operating according to the superposition principle, more especially such as are employed for tariff indicator control purposes, street lighting and boiler control purposes, meter tariff change over control purposes, and for other like purposes.

In systems of control operating according to this principle, i. e., the impulse transmission method (e. g., time of impulses, number of impulses, and the like) it is essential that the notefrequency control currents superimposed on the current flowing through the transmission line shall have an exactly constant frequency.

In order to generat such note-frequency control currents, there have been employed heretofore rotary frequency changers, or so-called note-frequency machines. The requisite high degree of constancy can, however, be obtained only with difiiculty and for short periods with rotary machines of this kind, since at each control impulse there occurs a shock due to the sudden increase in the load, which causes the rate of retation of the machine and therewith the frequency to drop. Even with the addition of highly A sensitive speed regulators this drop cannot be entirely avoided, and thus the use of such niachines for the purpose is not entirely satisfactory. Moreover, such frequency changing machines are very expensive, take up a considerable amount of space, and are costly because of the necessary use of complicated starting and regulating devices.

The object of the present invention is to obviate the above mentioned disadvantages to the use of note-frequency machines and to generat the note-frequency control currents required for note-frequency control installations operating on the superposition principle directly by static transformation, as by means of grid-controlled rectifiers (control rectifiers), which may, for example, be of a type commonly employed, uch as a grid controlled mercury arc type of rectifier, for feeding high frequency furnaces.

In this system the control rectifier is used to generate note-frequency control currents con sisting of short impulses which actuate suitable receivers according to the impulse-transmission method (time of impulses or number-of-impulses) as desired.

It is possible with thi invention to use the same network from which the transformer draws the low frequency energy required for the generation of the note-frequency currents, as a superposition network, to which the rectifier delivers the note-frequency currents generated.

When employing such control rectifiers or transformer the difficulties and disadvantages mentioned in respect to note-frequency machines or rotary converters are obviated, since with the use of a static control transformer or rectifier no mechanical mass inertia comes into play and, therefore, the frequency of the superposed currents supplied is quite independent of the load on the transformer.

By the use of such a static control transformer or rectifier very great control outputs can be obtained, so that extended network can be supplied With superposed currents from a single source.

The accompanying drawing shows by way of example one lay-out of a note-frequency control installation constructed according to the invention.

In this example, the installation consists essentially of the impulse transmitter l embodying a board or casing 2 carrying a series of contacts 2a, a receiver l d of similar type to the transmitter l and embodying a board or casing 3 carrying a series of contacts 3a and a rotary switch member 32), a receiving relay 4 connected in series therewith, and a plurality of receivers 5, 6, 7, etc., to be controlled, also of a single phase network 10 coupled to the polyphase network 8 through the transformer 9. Between the two networks 8 and !B there is connected the control transformer l I.

In detail there is the following arrangement of connections:

The primary of the polyphase transformer 9 is adapted to be connected through a suitable switch to the polyphase network 8, and the secondary of said transformer is connected to the primary of the single phase transformer I2, which in turn is connected through a group of condensers l4, arranged in parallel as shown, to the anodes llallf of a mercury arc type of vapour rectifier H having the controlling grids The neutral point of the polyphase transformer 9 is connected through a voltage smoothing inductance l3 to the cathode is of the rectifier l I. To one side of the secondary of the transforme l2 there is adapted to be connected through the line 23, 24 the primary winding 2i of the output transformer 22, and to the other side of the secondary of the transformer is connected the grid-controlling device l8, which is of the rectifier I l.

The connections of the control rectifier I I with the polyphase transformer 9, the single phase transformer I2, the voltage smoothing coil I2- and the current smoothing condensers M afford on the polyphase side a symmetrical loading of all three phases and permits a sine wave current to be supplied through the transformer 22 to the single phase network I 0.

The above indicated controlling device I8, which may be static (electrical) or mechanical, adapts the rectifier even under varying loads to supply current of exactly constant frequency to the network Ill, since there are no fluctuating changes in condition in the line 23, 24 to alter its inductance.

In the line 23, 24, which runs from the transformer I2 to the transformer 22, there is arranged the key 25 (safety or the like) operatively connected to the impulse transmitter I, such key being closed in a known manner by the transmitter mechanism at the beginning of each individual impulse and opened at the end of such impulse. The impulse transmitter I is connected to the pilot lines 26, 21, 28, etc., and associated press button switches 26a, 21a, 28a. Each press button switch is arranged in a definite pilot line to close the same for a definite impulse transmission through its particular line and through the transformer 2|, 22 and line It to the receiving relay 4 and the contact selector 3b, which is synchronized with the transmitting selector 2b and of the same phase therewith and from selector 2b to the particular receiver 5, 6, or 7, etc, to be controlled. The condensers I connected in the line 23, 24 serve to block the frequency of the network Ill from the transmitting and rectifier circuits. Relay 4 of the receiver may per form with respect to the receiver the same function as the starting switch of the transmitter.

The method of operation of the above described installation is as follows:

If a remote control operation is to be carried out and a definite order or a predetermined number or timed series of impulses for this purpose transmitted, the desired one of the press button switches 26a, 21a, 28a, etc., is pressed, whereby the key 25 is closed for a short time through the transmitter I with contact selector 2?), and thus the selected note-frequency control current impulses are superposed on the network It, the order or instruction determined by the transmission of impulses being transmitted through the receiving relay 4 and the receiving contact selector 3b to the proper receiver 5, 6 or I, etc., as the case may be, as will be readily understood.

The receiver la and transmitter I may be of the synchronous selector type in which the rotary switch member 2a, engageable with the stationany contacts 2b of the transmitter, and the rotary switch member 3a engageable with the stationary contacts 3b at the receiving station, are each driven by a synchronous motor operating in connection with a starting switch and embodyin means at th transmittin station for producing instruction order impulses of a selected member and/or duration, and means at the receiving station, conventionally illustrated at 5, '8 and 7, influenced by different instruction order impulses to operate devices controlled thereby. The means at the transmitting station for producing the instruction orders may consist of circuit make and break devices, each in a circuit including a contact 2a and a pilot line 26, 27 or 2B and adapted to be closed by the proper switch 26a, 27a or 28a to close the starting switch and set the motor at said station into action, the rotary switch member 26 being returned to zero position at the end of each transmitting action and a suitable clockwork mechanism, if desired, being employed to govern the time period of transmission or duration of the impulses. Any number of selector switch contacts may be employed in the contact selector at each station, each in association with a pilot line, in case of switch 2?), and a receiver line, in case of switch 3b. Only three such pilot lines and three such receiver lines are shown in the present instance, but any number up to the full number of contacts may be employed. It will be understood that the rotary switches at the transmitting and receiving stations are essentially duplicated and driven at the same speed by the respective synchronous motors so that their working positions will always correspond. The relay 4 at the receiving station may, as before stated, serve as the starting switch at such station or control a starting switch of usual type.

By this novel combination of a static frequencytransformer with a note-frequency remote control installation, as set forth, the control rectifier may be employed in a remote control system to secure high eihciency of action and in an economically advantageous manner.

Having thus described my invention, I claim:

1. In a note frequency remote control apparatus employing a polyphase supply network and a single phase transmission network, a vapor electric control rectifier for converting the polyphase current into pulsating current of constant frequency, said rectifier including a plurality of anodes with associated grids and a cathode, a polyphase transformer and a single phase transformer coupling the rectifier to the polyphase network, said polyphase transformer having its primary connected to the polyphase network and its secondary to the primary of the single phase transformer, and said single phase transformer having its primary connected by branches with the anodes, condensers arranged in parallel in said branches, a control device connected with the cathode, the grids and the secondary of the single phase transformer, output connections between the secondary of the single phase transformer and the transmission network including input and output portions, a make and break switch between said portions and an output transformer in the output portion, a synchronous transmitter governing said switch and embodying selective means for transmitting selected current impulses of constant frequency to the transmission network, and a synchronous receiver having a series of stations and selective means responsive to the transmitted impulses to transmit the same to the selected station.

2. In a note frequency remote control apparatus employing a polyphase supply network and a single phase transmission network, a vaporelectric control rectifier for converting the polyphase current into pulsating current of constant frequency, said rectifier including a plurality of anodes with associated grids and a cathode, a polyphase transformer and a single phase transformer coupling the rectifier to the polyphase network, said polyphase transformer having its primary connected to the polyphase network and its secondary to the primary of the single phase transformer, and said single phase transformer having its primary connected by branches with the anodes, condensers arranged in parallel in said branches, a control device connected with the cathode, the grids and the secondary of the single phase transformer, a conductor connecting the neutral point of the polyphase transformer with the cathode and having a voltage smoothing coil arranged therein, output connections between the secondary of the single phase transformer and the transmission network including input and output portions, a make and break switch between said portions and an output transformer in the output portion, a synchronous transmitter governing said switch and embodying selective means for transmitting selected current impulses of constant frequency to the transmission network, and a synchronous receiver having a series of stations and selective means responsive to the transmitted impulses to transmit the same to the selected station.

3. In a note frequency remote control apparatus employing a polyphase supply network, and a single phase transmission network, a vapor-electric control rectifier for converting the polyphase current into pulsating current of constant frequency, said rectifier including a plurality of anodes with associated grids and a cathode, a polyphase transformer and a single phase transformer coupling the rectifier to the polyphase network, said polyphase transformer having its primary connected to the polyphase network and its secondary to the primary of the single phase transformer, and said single phase transformer having its primary provided with branches connecting the anodes in pairs, each branch having a condenser arranged in parallel therein, a control device connected with the cathode, the grids and the secondary of the single phase transformer, a conductor connecting the neutral point of the polyphase transformer with the cathode and having a voltage smoothing coil arranged therein, output connections between the secondary of the single phase transformer and the transmission network including input and output portions, a make and break switch between said portions and an output transformer in the output portion, a synchronous transmitter governing said switch and embodying selective means for transmitting selected current impulses of constant frequency to the transmission network, and a synchronous receiver having a series of stations, 2, starting relay and selective means responsive to the transmitted impulses to transmit the same to the selected station.

HANS FROHLICH. 

